This study finds that New York's drug courts have a modest positive impact on rearrest and reconviction. However, they differ significantly in policies and practices, resulting considerable variation in impact. The most effective drug courts served higher risk and felony defendants, maximized their legal leverage, imposed certain sanctions, included prosecutor and defense representatives on the drug court team, made greater use of residential treatment for key populations, and employed evidence-based practices. Findings were drawn from a sample of 86 drug courts statistically matched with conventional courts.